Youngblood Geri L, Sweet Douglas H
Department of Pharmaceutical Sciences, Medical University of South Carolina, Charleston, SC 29425, USA.
Am J Physiol Renal Physiol. 2004 Aug;287(2):F236-44. doi: 10.1152/ajprenal.00012.2004. Epub 2004 Apr 6.
An uncharacterized murine cDNA clone was identified and, through sequence, phylogenetic, and functional analysis, determined to encode the newest member of the organic anion transporter family, organic anion transporter 5 (Oat5; Slc22a19). The Oat5 cDNA clone contained an insert 1,964 bp in length with a predicted open reading frame (from bp 84 to bp 1,739) coding for a peptide 551 amino acids long. Slc22a19 was localized to mouse chromosome 19 near the genes encoding Oat1 (Slc22a6) and Oat3 (Slc22a8). Northern blot analysis revealed Oat5 is highly expressed in the kidney of adult mice and rats. No sexual dimorphism in renal or hepatic expression of Oat5 was observed. Unlike Oat1-3, Oat5 expression was not detected in the choroid plexus of either mice or rats. Murine Oat5-expressing Xenopus laevis oocytes supported increased accumulation of the mycotoxin ochratoxin A, compared with water-injected control oocytes. This uptake was significantly inhibited by probenecid and the organic anions 2,4-dichlorophenoxyacetic acid, salicylate, and estrone sulfate but not by para-aminohippurate or urate. Transport of ochratoxin A by murine Oat5 was saturable, with an estimated K(m) of 2.0 +/- 0.45 microM. Oat5-mediated transport was neither cis-inhibited nor trans-stimulated by the dicarboxylate glutarate. Uptake was also completely unaffected by short-circuiting of the membrane potential. Thus the motive forces behind Oat5 function, which provide insight into its membrane localization, need to be further resolved. These data demonstrate for the first time that this newly identified gene encodes a protein that functions as an organic anion transporter.
通过序列、系统发育和功能分析，鉴定出一个未表征的小鼠cDNA克隆，确定其编码有机阴离子转运体家族的最新成员——有机阴离子转运体5（Oat5；Slc22a19）。Oat5 cDNA克隆包含一个长度为1964 bp的插入片段，其预测的开放阅读框（从第84 bp到第1739 bp）编码一个551个氨基酸长的肽段。Slc22a19定位于小鼠19号染色体上，靠近编码Oat1（Slc22a6）和Oat3（Slc22a8）的基因。Northern印迹分析显示，Oat5在成年小鼠和大鼠的肾脏中高度表达。未观察到Oat5在肾脏或肝脏表达中的性别差异。与Oat1 - 3不同，在小鼠或大鼠的脉络丛中均未检测到Oat5的表达。与注射水的对照卵母细胞相比，表达小鼠Oat5的非洲爪蟾卵母细胞支持霉菌毒素赭曲霉毒素A的积累增加。丙磺舒以及有机阴离子2,4 - 二氯苯氧基乙酸、水杨酸盐和硫酸雌酮可显著抑制这种摄取，但对对氨基马尿酸盐或尿酸盐无抑制作用。小鼠Oat5对赭曲霉毒素A的转运是可饱和的，估计米氏常数（K(m)）为2.0±0.45 μM。Oat5介导的转运既不受二羧酸盐戊二酸的顺式抑制，也不受其反式刺激。膜电位短路对摄取也完全没有影响。因此，Oat5功能背后的驱动力（这有助于深入了解其膜定位）需要进一步解析。这些数据首次证明，这个新鉴定的基因编码一种作为有机阴离子转运体发挥功能的蛋白质。
